1. Field of the Invention
The present invention relates to a secondary battery pack, and more particularly, the present invention relates to a conductive plate for preventing the bending of a battery pack due to swelling when charging a battery pack containing at least two batteries and further relates to a secondary battery pack using such a conductive plate.
2. Description of the Related Art
Recently, compact and light-weight electrical and electronic devices, such as cellular phones, notebook computers, camcorders and so on are being developed and manufactured. An electrical battery pack is embedded into these devices so that these portable electrical and electronic devices may be operated even in places where an additional power source is unavailable. The embedded battery pack includes at least two batteries inside of it so that a voltage of a predetermined level may be outputted, thereby driving the portable electrical and electronic devices.
Recently, in light of the economic situations, battery packs employ a secondary battery in which charging and discharging is possible. Such secondary batteries include Nickel-Cadmium batteries (Ni—Cd), Ni-Hydrogen batteries (Ni-MH), Lithium (Li) batteries and Lithium ion batteries.
In most of such secondary batteries, an electrode assembly composed of an anode, a cathode and a separator are contained in a can formed of aluminum or an aluminum alloy, a cap assembly is mounted on the can, the electrolyte is injected into the can, and the can is sealed. The can may be formed of a ferrous metal, but if it is formed of aluminum or an aluminum alloy, the battery can be light-weight, corrosion-proof, and have improved characteristics under high-voltage.
A conventional battery pack described above, and shown in FIG. 1, includes at least two battery cells 1 and 2 arranged in a thickness direction thereof, and electrode terminals 1a and 2a of different polarities which are electrically connected via a conductive plate 3.
However, in the past, as shown in FIG. 2, when each battery is charged to 100%, the center portion thereof is raised due to swelling. Therefore, the end of the battery pack in which the batteries are not connected by the conductive plate is widened more than the end of the battery pack in which the batteries are connected by the conductive plate.
In this way, if the angle θ formed at the end of the battery pack in which the batteries are not connected by the conductive plate becomes large, the entire battery pack is bent into a V shape, and thus there is a problem in that a space larger than the space occupied by the original battery pack is needed. That is, the thickness of the entire battery pack increases.